1. Field of the Disclosure
The present disclosure relates to a rotation detector capable of detecting a change in angle of rotation of a rotating unit and determining whether the rotating unit has rotated to a predetermined position.
2. Description of the Related Art
Detectors detecting a moving magnet with a magnetic detecting element have been used in variety of fields.
Japanese Patent No. 5059772 discloses a magnetic angular position sensor which detects rotation of a cylindrical permanent magnet with two magnetosensitive elements.
The magnetic angular position sensor disclosed in Japanese Patent No. 5059772 includes the cylindrical permanent magnet which is attached to an outer circumferential surface of a steering column or a drive shaft. The permanent magnet is radially magnetized. The magnetosensitive elements each include at least one pair of magnetic sensors (magnetoresistive sensors) magnetically coupled by a ferromagnetic yoke which is orthogonal to the sensing axes of the sensors. The yoke is disposed in a plane orthogonal to the axis of rotation of the magnet or a plane parallel to a plane passing through the axis of rotation.
Two signals obtained by detection through the two magnetosensitive elements are subjected to decoding and standardization of two components, thus producing an electrical signal which is proportional to the angle of rotation of the magnet.
U.S. Pat. No. 6,060,969 discloses a switch including a magnet and a magnetic detecting element (magnetoresistive element).
The switch disclosed in U.S. Pat. No. 6,060,969 includes a magnetic angle sensor fastened inside a housing. The housing accommodates the magnet moving together with a switch head. The magnet moves over the magnetic angle sensor. As the magnet moves, the magnetic angle sensor detects a change in magnetic field component parallel to a moving direction in which the magnet moves and a change in magnetic field component in a direction orthogonal to the moving direction.
In general, an apparatus, like that disclosed in Japanese Patent No. 5059772, for detecting the angle of rotation of a magnet and a switch, like that disclosed in U.S. Pat. No. 6,060,969, for detecting movement of a magnet are configured as separate apparatuses. There has been no apparatus that provides both an output (hereinafter, referred to as a “rotation detection output”) indicating detected rotation and an output (hereinafter, referred to as a “switch output”) from a switch with a single magnet.
To produce switch outputs from two or more switch systems, any of switch detecting units has to be offset from the middle of a magnet along the width (hereinafter, also referred to as a “width direction”) of the magnet. In this case, magnetic field components in different directions from the magnet are applied to the switch detecting units, so that noises of the magnetic field components other than the magnetic field components to be detected in target directions tend to be superimposed on the detected magnetic field components in the target directions. Disadvantageously, it is difficult to yield high-precision switch outputs.
These and other drawbacks exist.